Children who attend schools with more traffic noise show slower cognitive development

Summary: A new study reports that children who go to school near busy roads and traffic are more likely to have a deficiency in working memory and attention.

source: Barcelona Institute for Global Health

Road traffic noise is such a pervasive problem in cities that its impact on children’s health is still poorly understood.

A new study conducted in 38 Barcelona schools indicates that school traffic noise has a detrimental effect on the development of working memory and attention in primary school students.

The results of this study, led by the Barcelona Institute for Global Health (ISGlobal), have been published in Medicine PLoS.

The study, which forms part of the BRREATHE project led by researchers Maria Foraster and Jordi Sunyer, included 2,680 children between the ages of 7 and 10.

In order to assess the potential impact of traffic noise on cognitive development, researchers focused on two abilities that develop rapidly during pre-adolescence and are central to learning and academic achievement: attention and working memory.

Attention includes processes such as selective attention to specific stimuli or focusing on a specific task for an extended period of time.

Working memory is the system that allows us to store and manipulate information in the mind over a short period of time. When we need to process information stored in working memory continuously and efficiently, we use what is known as complex working memory.

Fieldwork for the study was carried out over a 12-month period in 2012 and 2013, with participants completing cognitive tests four times. The aim of these tests was not only to assess working memory and attention, but also to study its development over time.

During the same period, noise measurements were performed in front of the 38 participating schools, as well as on playgrounds and within classrooms.

At the completion of the year-long study period, the results showed that the progression of working memory, complex working memory, and attention was slower in students who attended schools with high levels of traffic noise.

For example, an increase in external noise levels of 5 dB resulted in the development of a working memory that was 11.4% slower than the average and the development of a complex working memory of 23.5% slower than the average.

Similarly, exposure to 5 dB of outside traffic noise developed attention capacity 4.8% slower than average.

The differences between inside and outside the classroom

In an analysis of external noise in schools, both higher average noise level and greater fluctuations in noise levels were associated with poorer student performance on all tests. Within the classroom, greater fluctuation in noise levels was also associated with slower progress throughout the year on all cognitive tests.

However, children exposed to higher levels of classroom noise throughout the year performed worse than students in quieter classes only on the attention test, but not on the working memory tests.

“This finding suggests that the noise peak within the classroom may be more disruptive to neurodevelopment than the average decibel level,” commented Maria Forster, a researcher at IS Global, the study’s lead author.

“This is important because it supports the hypothesis that noise characteristics may be more influential than average noise levels, despite the fact that current policies rely only on average decibels.”

“Our study supports the hypothesis that childhood is a period of impairment during which external stimuli such as noise can influence the rapid process of cognitive development that occurs before adolescence,” explained ISGlobal researcher Jordi Sunyer, the study’s latest author.

Exposure to noise in the home

The researchers used the 2012 Barcelona road traffic noise map to estimate the average noise level in each participant’s home. However, in this case, no association between residential noise and cognitive development was observed.

This shows two little girls doing schoolwork
Attention includes processes such as selective attention to specific stimuli or focusing on a specific task for an extended period of time. The image is in the public domain

“This may be because exposure to noise in school is more harmful as it affects poor windows for concentration and learning processes,” commented Maria Forster.

On the other hand, although noise measurements were taken in schools, noise levels in children’s homes were estimated using a noise map that may be less accurate and, in any case, reflect only external noise. This may also have affected the results.”

The study adds to the body of evidence about the effects of transportation on children’s cognitive development, which has so far been observed in schools exposed to aircraft noise as well as in schools exposed to traffic-related air pollution.

The researchers emphasized the need for further studies of road traffic noise in other population groups to determine whether these preliminary findings can be extrapolated to other cities and places.

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author: press office
source: Barcelona Institute for Global Health
Contact: Press office – Barcelona Institute for Global Health
picture: The image is in the public domain

original search: open access.
Exposure to road traffic noise and cognitive development in schoolchildren in Barcelona, ​​Spain: a population-based cohort studyWritten by Maria Forrester et al. MEDICINE PLOS


Exposure to road traffic noise and cognitive development in schoolchildren in Barcelona, ​​Spain: a population-based cohort study


Road traffic noise is a common and known health hazard. However, little is known yet about its effect on children’s cognition. We aimed to study the association between exposure to road traffic noise and the development of working memory and attention in primary school children, considering average annual noise levels in outdoor, school and indoor and noise variability characteristics, as well as exposure to noise in the home and in the air. The open.


We followed a population sample of 2,680 children aged 7-10 years from 38 schools in Barcelona (Catalonia, Spain) between January 2012 to March 2013. The children underwent computerized cognitive tests 4 times (n = 10,112), for working memory (two-way background task, detectability), complex working memory (triple background task, detectability), and inattention (attention network task, standard error reaction time, milliseconds).

Road traffic noise indoors and outdoors in schools, at the beginning of the school year, was measured using standard protocols to obtain A-weighted equivalent sound pressure levels, that is, annual mean levels scaled to fit human hearing, during the day (LAeq in daytime, in dB). ). We also extracted variability indices from the measurements (intermittent noise percentage, %; number of noise events) and obtained individual estimated indoor noise levels (LAeq) to correct for class orientation and class change between years.

Indoor and outdoor noise exposures in the home (Lden, ie EU index of 24-h annual mean levels) were estimated using the 2012 Barcelona Noise Map, according to the European Noise Directive (2002).

We used mixed linear models to assess the relationship between noise exposure and cognitive development to adjust for age, gender, maternal education, and the home, indoor, or outdoor socioeconomic vulnerability index associated with air pollution (TRAP) for the corresponding school models or outdoor nitrogen dioxide (No.2) for home models. Child and school were included as overlapping random effects.

The median age (25th percentile, 75th percentile) of the children at visit 1 was 8.5 (7.8; 9.3) years, 49.9% of girls, and 50% of schools were public.

School outdoor exposure to traffic noise was associated with slower development of working memory (2-noon and 3-noon) and increased inattention over 1 year in children, both for an average noise level (eg, 4.83 points [95% CI: ‒7.21, ‒2.45]And the s– value <0.001, in binary background detectability per 5 dB at street levels) and noise variability (eg, 4.38 [‒7.08, ‒1.67]And the s– value = 0.002, for every 50 street-level noise events). Single exposure to average noise level of classroom road traffic was only associated with inattention (2.49 ms .). [0, 4.81]And the s-value = 0.050, per 5 dB), while internal noise fluctuation was consistently correlated with all results.

Noise exposure at home and abroad was not associated with outcomes. Study limitations include a possible lack of generalizability (58% of mothers with a university degree in our study versus 50% in the district) and a lack of prior assessment of noise exposure.


We observed that exposure to road traffic noise at school, but not at home, was associated with slower development of working memory, complex working memory, and attention of school children over 1 year. Correlations with indices of noise variability were more pronounced than average noise levels in the classroom.